Which of the following would NOT make a sledgehammer unusable?

An intact grip on a sledgehammer is essential for its usability, providing a secure hold and allowing the user to swing the hammer effectively and safely. If the grip is intact, it indicates that the user can maintain control over the tool during use, which is crucial for both performance and safety.

In contrast, having a rounded head, a loose head, or a damaged handle would compromise the functionality of the sledgehammer. A rounded head may impair its ability to deliver a focused impact on the surface being struck. A loose head poses a significant safety risk, as it can detach during use, potentially causing injury. A damaged handle, on the other hand, could break or splinter, leading to loss of control. Therefore, the presence of an intact grip distinctly allows for continued effective usage of the tool, while the other options directly hinder its effectiveness.